The textile industry utilizes multi-positional commercial spinning machines capable of winding multiple spindles of identical product. One type of commercial yarn producing machine, known as a ring spinning machine, directly produces a staple yarn. The production throughput of such a machine is relatively limited.
Another direct spinning apparatus, which for the purpose of this application is referred to as a “stretch-break” apparatus, improves throughput by producing staple yarn directly from a multi-filament yarn feed in a continuous operation. Shown within the dotted box in FIG. 1 is a schematic view of the functional and enabling elements of a single position 12A of a stretch-break apparatus generally represented by reference character 10. One or more additional stretch-break positions 12B, 12C, . . . 12N, each identical to position 12A, may be provided to define a multi-position apparatus 10. The apparatus 10 is disclosed and claimed in co-pending application Ser. No. 09/979,808, published internationally on Dec. 21, 2000 as WO 0077283.
Throughout the following description of the stretch-break apparatus it should be appreciated that each roll in a position may be implemented as multiple rolls, with or without associated nip rolls. It should also be understood that the pressure exerted by the nip rolls may be controlled, either manually or by an associated control device.
The position 12A includes a drawing and annealing zone 20, a first break zone 30, a second break zone 40 (also known as a re-break zone), and a consolidation zone 50 connected in series between a continuous supply 16 of yarn Y and a windup zone 60.
The yarn supply 16 may include an unwinder 18 driven by enabling unwind controller 19, as shown, or another suitable yarn supply device. The unwind controller 19 may be implemented by a braking mechanism or an unwind motor to control the tension of the yarn Y fed from the unwinder 18.
The drawing and annealing zone 20 is defined between a roll 22 and a driven roll 26 and includes a hot plate 24. The roll 22 includes an enabling heater 22H and the hot plate 24 includes an enabling heating element 24H. The roll 26 may also include an enabling heater 26H. As is well known, to impart draw action, driven roll 26 must rotate at a higher surface speed than the surface speed of the heated roll 22. The ratio of the surface speed of roll 26 to the surface speed of roll 22 is termed “draw ratio”.
The first break zone 30 is defined between rolls 26 and 34, and the second break zone 40 is defined between rolls 34 and 42. The ratio of the surface speed of roll 34 to the surface speed of roll 26 is termed “stretch-break ratio”, while the ratio of the surface speed of roll 42 to the surface speed of roll 34 is termed “re-break ratio”. An optional jet 32 with enabling air supply 32S may be included in the first break zone 30. The second break zone 40 may include an optional jet 36 with an associated enabling air supply 36S.
The consolidation zone 50 is defined between rolls 42 and 56 and may include one or more consolidation jets 52 and its enabling air supply 52S. The consolidation device may also be a mechanical or other fluid device designed to consolidate the yarn Y. The ratio of the surface speed of roll 56 to the surface speed of roll 42 is termed “consolidation ratio”.
The windup zone 60 includes a traversing winder 62 for collecting the finished staple yarn S on a bobbin B. The winder 62 has an associated enabling winder and traverse drives 62D, 62T. A waste jet 58 and it enabling-air supply 58S may directly precede the winder 62 to facilitate stringing. The ratio of the surface speed of winder 62 to the surface speed of roll 56 is termed “Take Up Tension” (in the table of FIG. 4).
Individual rolls that sequentially contact the yarn Y during the stretch-break process may be paired into operational roll-sets. Thus, rolls 26, 34 may define a first roll-set 30S, rolls 34, 42 may define a second roll-set 40S, and rolls 42, 56 may define a third roll-set 50S. Each roll 22, 26, 34, 42, and 56 has an associated enabling drive motor 23, 27, 35, 43, and 57 respectively.
Alternatively, as seen in FIG. 1A, the roll 34 may be functionally implemented by multiple rolls, such as dual rolls 34A, 34B. Similarly, roll 42 may be functionally implemented by multiple rolls, such as dual rolls 42A, 42B. In such an alternative configuration rolls 26, 34A; rolls 34B, 42A; and rolls 42B, 56 may define operational roll-sets 30S′, 40S′, 50S′, respectively. Rolls 34A, 34B, 42A, and 42B have associated drive motors 35A, 35B, 43A, and 43B respectively.
In operation, yarn Y comprised of filaments F is introduced into the drawing and annealing zone 20. Within the drawing and annealing zone 20 the yarn Y is heated to an annealing temperature by the combination of the heater 22H within the heated roll 22 and the hot plate 24. The first roll 22 in the drawing and annealing zone 20 grips the incoming filaments F and the second roll in the operational roll-set (i.e., roll 26) draw-stretches the same. The surface speed of roll 26 may be set relative to the surface speed of roll 22 to draw the heated yarn Y, if desired, to obtain desired tensile properties.
The annealed yarn Y passes into the first break zone 30. During steady state operation, the first roll 26 in the break zone 30 grips the annealed filaments and the second roll in the operational roll-set, i.e., roll 34 (FIG. 1) or roll 34A (FIG. 1A), as the case may be, draw-stretches them until all of the filaments F break in a random manner. The filaments F may be further broken in the second break zone 40 located downstream from the first break zone 30. An optional jet 36 may be used to control ends of filaments broken in the first break zone to prevent roll wraps.
The yarn Y is then consolidated in the consolidation zone 50 to form a staple yarn S. The staple yarn S is wound on the bobbin B under controlled tension and traverse speed by the winder 62.
The stretch-break process as implemented in the apparatus 10 is particularly difficult to start, since the dynamic stretching and breaking properties of a yarn differ at various speeds and differ from its static properties. The goal of the stretch-break process is to break all of the filaments randomly in both time and location. In the apparatus of FIG. 1 all the filaments are broken randomly in the first stretch-break zone 30, and those broken filaments are re-broken randomly in the second re-break zone 40. Aggressive starting could result in simultaneous complete breakage of all filaments in either zone, resulting in loss of string-up of the yarn through the apparatus and generation of waste product.
Startup is particularly complicated by the interaction of process parameters. For instance, the stretch-break tolerance (i.e., the breakage of some filaments without complete breakage) of the yarn is affected by the annealing temperature, which changes throughout startup. The stretch-break tolerance of the yarn also changes significantly as roll speeds, and the relative speed ratio of rolls in a given roll-set, vary throughout startup. Jet parameters, particularly operating pressure, affect the degree of fiber entanglement, and winding parameters, such as winding tension, also affect the yarn's stretch-break tolerance.
In view of the foregoing is believed to be beneficial to provide a computer-implemented method for controlling the transition from an initial to a steady state condition of a single or multi-position stretch-break process that minimizes the possibility of complete yarn breakage and waste. It is believed of further advantage to be able to control the process parameters in accordance with a predetermined “recipe” tailored to each individual yarn. As used herein the term “recipe” is a predetermined sequence of changes of operational parameters for the various enabling elements in each position of the stretch-break apparatus. For example, a given recipe will specify sequential changes in the speed of each roll in coordination with the change in speed of at least one other roll (i.e., the ratio of speeds in a given roll-set), the temperature of each heater or heated roll, the operating parameter (i.e., pressure state) of associated jet(s), and the winder tension, to cause a processing position to transition from a stopped or initial condition to a steady state operating condition. The transitions of parameters may be varied in a step-wise or continuous manner.